Fill a PET-bottle with contaminated water. Leave it out in the sun. Wait a while... and the water is safe to drink.

This is not a miracle. SODIS (Solar Water Disinfection) is a natural process, in which the UV-radiation of the sun inactivates certain harmful pathogens in the water. The process only requires PET-bottles, which are filled with contaminated water and are then exposed to the sun. The duration of this disinfection process varies and depends on the sun’s UV intensity. Today, SODIS is used by around five million people worldwide. Do you think it?

Users of the SODIS method are unable to estimate the time needed for the water to be safely disinfected. Then Martin Wesian and Helioz GmbH, an Austrian social enterprise come in. Using a small solar-powered UV-measurement device called WADI (WAter DIsinfection) that is screwed onto the mouth of the PET-bottle containing water, it has helped make the whole process calculable. As soon as the water is safe to drink, a sad face on WADI turns into a smiley. That is so easy.

As SODIS method depends on favorable climate, it is recommended to use WADI anywhere between 35° north and 35° south of the equator, where, on average, annual sunshine hours are abundant. This includes the majority of the countries with people lacking access to improved drinking water sources.

Moreover, WADI is completely green. There is no batteries required and it is free from harmful and toxic substances.

It is easy to get one for 23-30 EUR: there is a webshop on the webpage of Helioz GmbH

You can read our interview below with ideas owner, Martin Wesian.

How did the idea of WADI come up?

WADI is based on a scientifically proven method called SODIS (Solar Water Disinfection), established by the Swiss Federal Institute of Technology Zurich (ETH Zurich). It has been proven that there is disinfection of contaminated water filled into PET-bottles by sunrays.

I have read an article of SODIS founder Martin Wegelin in Der SPIEGEL and started to conceptualize.

What is WADI?

WADI is an easy-to-use and inexpensive UV-measurement device that is developed especially for low-income households in Africa, Asia and South America.

WADI on Bottles

WADI device on the bottle in use.                  Photo: Helioz GmbH

How does it work?

WADI measures the relevant UV-rays of the sun and indicates a smiley face as soon as the water is ready to drink. WADI guarantees a disinfection rate of at least 3-log, thus 99,9% of germs (of common coliform bacteria) - which cause waterborne diseases - have been inactivated. This has been approved by several organizations and universities all around the world.

When and how was your social company founded? What is the mission of Helioz?

Helioz GmbH has been founded in June 2010, its long term goal is to become a valuable and trusted developer and seller of our products for low-income households. Finally, the mission is to support people in low-income countries gaining basic needs like clean water but especially to give self-determination.

WADI Uganda

Photo with WADI from Uganda .                          Photo: Helioz GmbH

Which countries does Helioz collaborate with? How many WADIs are already in use all over the World?

WADIs are currently delivering potable water in Ethiopia, Philippines, Uganda, Papua New Guinea and some more. Helioz’ distribution partners are covering more than 40 countries worldwide.

You have received several awards from the beginning. What is the most significant for you?

That’s a question hardly to answer. Each of them brought high recognition and self-confidence to be on the right path and especially, a lot of valuable contacts. Most of our distribution partners asked us to be allowed selling WADI.

(Their latest recognition was taken in Madrid in October 2014. Helioz was among the finalists of the 3rd Social Innovation Tournament organized by European Investment Bank Institute. Besides, they have Sustainable Future Award (Vienna, 2013), Social Investment Pioneer Award in Social Business Category (Colombia, 2013), Water Innovations Award, in Category of Best Ethical or Humanitarian Initiative (Rio de Janeiro, 2011) and so on.)

MartinWesian Helioz

Martin Wesian, the inventor and founder of Helioz GmbH.                 Photo: Helioz GmbH

What is your idea about the future of WADI and Helioz?

Actually, WADI should be an interim solution allowing people to take their lifes in their own hands. Clean piped water is the final solution we are aiming at … but this will take a long time.

There will be a charity concert in Vienna for a WADI project in Uganda on 17th April 2015. What does it mean for Helioz?

These kind of charity events are very important for us to give Europeans a different view of the needs of people in respective countries. They don´t like being poor and they are willing and able to change this situation as soon as we give them a chance and the possibility to act self-determined.

Named charity event is for the Batwa Pygmies in Uganda, one of the eldest folk living in Africa. The mortality rate of children under five is more than 50%, mainly caused by waterborne diseases. We could change a lot with little money.


For futher information of WADI please click here.


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